Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kcle 121528 
afdcle

Area forecast discussion
National Weather Service Cleveland Ohio
1028 am EST Tue Nov 12 2019

Synopsis...
low pressure will track northeast reaching the New England
states later this morning. Arctic high pressure will then build
into region from the southwest tonight. This high will quickly
shift to the East Coast of the US by wedneday evening. This will
allow a clipper storm system to dive across the central Great
Lakes region on Thursday. Temperatures will be slightly below
average for the end of the week and weekend.

&&

Near term /through Wednesday/...
the Winter Weather Advisory was allowed to expire at 10 am this
morning for Erie, Huron, Ashland, and Wayne counties in Ohio.
Here, the lingering lake effect snow is expected to mainly be
light and should exit the area to the east by early afternoon.
Farther east, the Winter Weather Advisory and Winter Storm
Warning for lake effect snow remain valid. In addition, added
Mahoning County to the Winter Weather Advisory, which is in
effect until 7 PM this evening. Nam12 pop and quantitative precipitation forecast guidance has
been performing fairly well lately given observed trends over
the past couple hours. Thus, we may need to adjust pops, qpf,
and snowfall downward for our PA counties through this afternoon
due to the potential for significant low-level shear to limit
lake-induced instability. Will continue to evaluate for the
early afternoon update. A northwesterly low-level flow is
expected to continue triggering multiple lake effect snow bands
off Lake Erie with the potential for one or two stronger snow
bands tied to an upstream connection to Lake Huron. This
northwesterly flow of cold air will gradually back to westerly
and then west-southwesterly during Wednesday morning and early
afternoon, allowing the lake effect snow to pivot northeastward
and eventually retreat over Lake Erie.

Additional snow accumulations are expected to be highly
variable. These should average 1 to 3 inches in the advisory. In
the Ohio snowbelt portion of the Winter Storm Warning, 2 to 4
inches of new snow are expected, with localized amounts up to 7
inches possible where heavier bands persist the longest. This
may especially be the case in the higher terrain of Geauga
County. In the PA snowbelt, additional snowfall is forecast to
average 3 to 9 inches, with the greatest amounts in the higher
terrain of southern Erie and northern Crawford counties. The
rest of our near-term forecast remains valid.

Previous discussion...the synoptic snow system has moved out of
our area and we have transitioned into lake effect snow across
the primary and secondary snowbelt areas this morning. The main
upper level trough will move across the Great Lakes later today.
850 mb temperatures are still cooling and will eventually
bottom out around -15c over the area. Due to the nature of the
north-northwest to northwest flow with the first 10k above the surface, we can
expected multiple bands of lake effect to develop and impact
northeast Ohio and northwest Pennsylvania today into tonight.
The flow will become a little more westerly but lighter tonight.
This change should take the lake effect bands more into
northwest Pennsylvania tonight and eventually diminish by
Wednesday morning. We will continue the warning for the primary
snowbelt areas and the advisory as is for the secondary
snowbelt. Additional snowfall is expected with the heaviest
amounts where bands are able to persist across portions of
Geauga County and northeastward towards Erie County PA.

Tonight, skies will clear out for areas away from the lake and
lake induced clouds and snow. With fresh snowfall and an Arctic
high moving across the Ohio River valley tonight with lighter
winds, record low temperatures are likely areawide. There will
even be some single digit numbers where the winds are lightest
and skies clear out across western and central Ohio tonight and
Wednesday morning. See climate section below the current record
numbers.

The lake effect snow machine will cut off for our snowbelt areas
by Wednesday morning and a light southerly wind will return on
the back side of the Arctic high. Temperatures will still
struggle to reach above freezing again on Wednesday. Sunshine
will not be able to help because high and mid level cloudiness
will increase during the day from west to east ahead of the next
system.

&&

Short term /Wednesday night through Friday night/...
another shortwave trough will swing east across the forecast area
and precede a larger broad trough that will affect the eastern
United States during this period. Surface high pressure will build
east across the area and then move off the East Coast Thursday. A
surface trough as a reflection of the upper level trough will move
east across the area Thursday night followed by a cold front Friday.
Some residual lake effect will take place over the lake and possibly
along the immediate Lakeshore Wednesday night into Thursday.
Temperatures should warm enough to support mainly rain by Thursday
afternoon. As cold front shifts south across the area, colder air
will return and send flow back to northwest resulting in a
possibility for some More Lake effect Friday. Otherwise, generally
fair weather will dominate the rest of the forecast area through
this period under the influence of the high pressure. Surface trough
is expected to swing through the area dry along with the cold front
Friday. Lake snow could extend further inland over the northeast
portions of the forecast area by Friday night. Temperatures will be
moderating slightly through this period.

&&

Long term /Saturday through Monday/...
somewhat broad upper level ridge will move east over the region
Saturday into Sunday. Another broad upper level trough will move
east toward the area Monday. Otherwise, surface high pressure will
be the dominant weather feature across the area after the passage of
a cold front Friday. The high will build east across the central
Great Lakes Friday night and off the coast of Maine Sunday. A ridge
will extend back west over the Great Lakes into Monday. So, no real
threats of precipitation expected during this forecast period.
Further warming of temperatures is expected through the forecast
period as cold air retreats to the east and a return southerly flow
takes place on the back side of the high pressure.

&&

Aviation /12z Tuesday through Saturday/...
widespread MVFR/IFR conditions will continue today across the
snowbelt area of Northern Ohio into northwest Pennsylvania.
Ceilings and visibilities will vary in and around lake effect
snow bands. Areas of western and central Ohio will improve to
VFR this morning. Most of the Ohio airports will see VFR by this
evening and overnight. The lake clouds and lake effect snow
showers will linger the longest over northwest Pennsylvania overnight.
Northwest winds 10 to 15 knots are expected with gusts up to 25
knots. Winds will decrease by this evening and overnight as high
pressure starts to move into the area.

Outlook...non-VFR expected Tuesday night into early Wednesday
across NE Ohio/northwest PA in lake effect snow. Non-VFR possible
Wednesday night into Thursday, mainly NE Ohio/northwest PA.

&&

Marine...
low pressure will continue to move northeast of the area today and
gradient across the area will keep winds strong enough to support
Small Craft Advisory conditions through tonight. Flow shifts around
to a southerly direction Wednesday ending the Small Craft Advisory
threat. Flow gradually becomes westerly by Thursday night and then
northwest Friday as a cold front moves southeast across the lake.
Will likely need another Small Craft Advisory again Friday into
Saturday as winds shift around to the east by Saturday
afternoon.

&&

Climate...
Arctic air will move southeast into the local area today and
then begin to shift east tonight. The unseasonably cold air
will cause temperatures to plummet to some of the coldest
readings so far this season.

Below are the coldest temperatures on record for selected dates
at our six climate sites:

Tuesday, November 12:

Coldest high (year) coldest low (year)

Akron-Canton area: 28 (1920) 16 (1950)
Cleveland area: 31 (1920)18 (1911)
Erie area:34 (1996)18 (1911)
Mansfield area:29 (1996)16 (1976)
Toledo area:30 (1995)15 (1976)
Youngstown area: 30 (1996)19 (1950)



Wednesday, November 13:

Coldest high (year) coldest low (year)

Akron-Canton area:25 (1911)12 (1911)
Cleveland area: 22 (1911) 15 (1911)
Erie area: 23 (1911)16 (1911)
Mansfield area:27 (1986)13 (1986)
Toledo area:22 (1986)13 (1911)
Youngstown area:29 (1996)17 (1986)

&&

Cle watches/warnings/advisories...
Ohio...Winter Storm Warning until 10 am EST Wednesday for ohz011>014-
089.
Winter Weather Advisory until 7 PM EST this evening for ohz010-
020>023-033.
PA...Winter Storm Warning until 1 PM EST Wednesday for paz001>003.
Marine...Small Craft Advisory until 4 am EST Wednesday for lez144>149.
Small Craft Advisory until 11 PM EST this evening for lez142-
143.

&&

$$
Synopsis...Griffin
near term...Griffin/jaszka

National Weather Service Glossary of Abbreviations